A Brooklyn jury acquitted a man of setting a raging blaze that killed five people, including a toddler and a crippled elderly man – despite his own admission that he set the fire.

“I’m angry. [The jury] should have been paying attention,” said Darryl Gardner, whose father, James – bedridden since suffering a stroke – died inside the fire that was intentionally set in the lobby vestibule of 922 New York Ave. in East Flatbush.

Sunday will mark the first anniversary of the horrific fire that also killed 18-month-old Hadja Diallo, her mother Hadiatou Bah, 41, and her cousins Issiaga Diallo, 50, and Mamadou Lamarana, 30.

“It wasn’t their father,” fumed Gardner, 39, after the jury had cleared out of the courtroom.

“If it was their father or their relative, they would have paid attention.”

After three days of deliberations, the jury finally came back with a not guilty verdict on the arson charge against Rodney Williams, a neighborhood fixture prosecutors described as an alcoholic.

“It was a hung jury for a while,” said one of the jurors. “There was conflicting evidence.”

Williams first admitted to cops in a written statement that he started the blaze to scare the man abusing a friend of his, then reiterated that in a video statement.

“I didn’t want it to go outrageous,” Williams, 29, said on the tape in a very soft-spoken voice. He said he bought a 99-cent bottle of rubbing alcohol from a nearby bodega, doused some paper fliers before stuffing them under the second door of the vestibule.

He admitted on the tape that the fire was supposed to be “just a distraction.”

His lawyer, Sam Karliner, argued that detectives coerced his admission and that “it was a just verdict.”

One of the jurors cited for The Post a fire marshal’s testimony that the burn area was too big for the amount of alcohol that would have been in the bottle.

“There’s no way [the rubbing alcohol] went that far down the hallway,” the juror said, adding, “We didn’t feel prosecutors gave us enough to convict him.”

Despite the exoneration, Williams will still have to finish serving up to four years behind bars for a drug rap. He pleaded guilty last year to trying to sell drugs to an undercover cop.

“It’s painful when you know someone committed a crime like this,” said prosecutor Lawrence Fredella. “But the jury listened to all the evidence, and they came back with a verdict they thought was fair.”

That was not enough for Darryl Gardner.

“He admitted he started the fire,” Gardner said. “Now he’s free to do it again. An arsonist is an arsonist.”